feat(smb): support range header (close #3192)

drivers/smb/driver.go

@@ -3,12 +3,16 @@ package smb
 import (
 	"context"
 	"errors"
+	"io"
+	"net/http"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/alist-org/alist/v3/internal/driver"
 	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/pkg/http_range"
 	"github.com/alist-org/alist/v3/pkg/utils"
 
 	"github.com/hirochachacha/go-smb2"
@@ -79,10 +83,27 @@ func (d *SMB) Link(ctx context.Context, file model.Obj, args model.LinkArgs) (*m
 		d.cleanLastConnTime()
 		return nil, err
 	}
-	d.updateLastConnTime()
+	link := &model.Link{
-	return &model.Link{
 		Data: remoteFile,
-	}, nil
+	}
+	if args.Header.Get("Range") != "" {
+		r, err := http_range.ParseRange(args.Header.Get("Range"), file.GetSize())
+		if err == nil && len(r) > 0 {
+			_, err := remoteFile.Seek(r[0].Start, io.SeekStart)
+			if err == nil {
+				link.Data = utils.NewLimitReadCloser(remoteFile, func() error {
+					return remoteFile.Close()
+				}, r[0].Length)
+				link.Status = 206
+				link.Header = http.Header{
+					"Content-Range":  []string{r[0].ContentRange(file.GetSize())},
+					"Content-Length": []string{strconv.FormatInt(r[0].Length, 10)},
+				}
+			}
+		}
+	}
+	d.updateLastConnTime()
+	return link, nil
 }
 
 func (d *SMB) MakeDir(ctx context.Context, parentDir model.Obj, dirName string) error {

pkg/http_range/range.go

@@ -0,0 +1,107 @@
+// Package http_range implements http range parsing.
+package http_range
+
+import (
+	"errors"
+	"fmt"
+	"net/textproto"
+	"strconv"
+	"strings"
+)
+
+// Range specifies the byte range to be sent to the client.
+type Range struct {
+	Start  int64
+	Length int64
+}
+
+// ContentRange returns Content-Range header value.
+func (r Range) ContentRange(size int64) string {
+	return fmt.Sprintf("bytes %d-%d/%d", r.Start, r.Start+r.Length-1, size)
+}
+
+var (
+	// ErrNoOverlap is returned by ParseRange if first-byte-pos of
+	// all of the byte-range-spec values is greater than the content size.
+	ErrNoOverlap = errors.New("invalid range: failed to overlap")
+
+	// ErrInvalid is returned by ParseRange on invalid input.
+	ErrInvalid = errors.New("invalid range")
+)
+
+// ParseRange parses a Range header string as per RFC 7233.
+// ErrNoOverlap is returned if none of the ranges overlap.
+// ErrInvalid is returned if s is invalid range.
+func ParseRange(s string, size int64) ([]Range, error) { // nolint:gocognit
+	if s == "" {
+		return nil, nil // header not present
+	}
+	const b = "bytes="
+	if !strings.HasPrefix(s, b) {
+		return nil, ErrInvalid
+	}
+	var ranges []Range
+	noOverlap := false
+	for _, ra := range strings.Split(s[len(b):], ",") {
+		ra = textproto.TrimString(ra)
+		if ra == "" {
+			continue
+		}
+		i := strings.Index(ra, "-")
+		if i < 0 {
+			return nil, ErrInvalid
+		}
+		start, end := textproto.TrimString(ra[:i]), textproto.TrimString(ra[i+1:])
+		var r Range
+		if start == "" {
+			// If no start is specified, end specifies the
+			// range start relative to the end of the file,
+			// and we are dealing with <suffix-length>
+			// which has to be a non-negative integer as per
+			// RFC 7233 Section 2.1 "Byte-Ranges".
+			if end == "" || end[0] == '-' {
+				return nil, ErrInvalid
+			}
+			i, err := strconv.ParseInt(end, 10, 64)
+			if i < 0 || err != nil {
+				return nil, ErrInvalid
+			}
+			if i > size {
+				i = size
+			}
+			r.Start = size - i
+			r.Length = size - r.Start
+		} else {
+			i, err := strconv.ParseInt(start, 10, 64)
+			if err != nil || i < 0 {
+				return nil, ErrInvalid
+			}
+			if i >= size {
+				// If the range begins after the size of the content,
+				// then it does not overlap.
+				noOverlap = true
+				continue
+			}
+			r.Start = i
+			if end == "" {
+				// If no end is specified, range extends to end of the file.
+				r.Length = size - r.Start
+			} else {
+				i, err := strconv.ParseInt(end, 10, 64)
+				if err != nil || r.Start > i {
+					return nil, ErrInvalid
+				}
+				if i >= size {
+					i = size - 1
+				}
+				r.Length = i - r.Start + 1
+			}
+		}
+		ranges = append(ranges, r)
+	}
+	if noOverlap && len(ranges) == 0 {
+		// The specified ranges did not overlap with the content.
+		return nil, ErrNoOverlap
+	}
+	return ranges, nil
+}

pkg/utils/io.go

@@ -69,3 +69,25 @@ func (l limitWriter) Write(p []byte) (n int, err error) {
 func LimitWriter(w io.Writer, size int64) io.Writer {
 	return &limitWriter{w: w, limit: size}
 }
+
+type ReadCloser struct {
+	io.Reader
+	io.Closer
+}
+
+type CloseFunc func() error
+
+func (c CloseFunc) Close() error {
+	return c()
+}
+
+func NewReadCloser(reader io.Reader, close CloseFunc) io.ReadCloser {
+	return ReadCloser{
+		Reader: reader,
+		Closer: close,
+	}
+}
+
+func NewLimitReadCloser(reader io.Reader, close CloseFunc, limit int64) io.ReadCloser {
+	return NewReadCloser(io.LimitReader(reader, limit), close)
+}